#app {
  background-color: aquamarine;
  width: 1000px;
  height: 1000px;
  .app-child {
    width: 500px;
    height: 500px;
    background-color: antiquewhite;
  }
  .other-child {
    width: clamp(100px, 30%, 200px);
    height: 150px;
    background-color: red;
  }
}